In known manual and semi-automatic welding processes, location of component edge and surface height is typically reliant on an operators ‘hand to eye’ coordination. There may be some part-to-part variation in parts to be welded, including, for example, edge or surface variation between parts. Accordingly, it may be necessary to make adjustments to the welding process to accommodate for such part-to-part variation. Typically, this is achieved by manual operator adjustment. The quality of weld produced can therefore vary, depending on the skill of the operator. Control of component edge and surface height location in relation to the weld torch electrode position during welding is important, as variation of these parameters may have large impact on resultant weld quality. Variable weld quality between products is undesirable from a view of achieving high production repeatability between parts. Additionally, variable weld quality can lead to reduced predictability in estimating the expected lifetime of the welded product.
To remove or reduce the effect of manual operator influence on variability of the welding process, it is known to automate, or semi-automate, welding processes. However, this suffers a problem that robotic automation removes the visual feedback loop and control provided by the operator for detection of component edge location and surface height. Accordingly, where there is ‘part-to-part’ edge or surface variation, there remains a problem of variation in weld quality, and repeatability of the welding process, even in an automated or semi-automated process.